The present invention relates to headphone systems of the type used with home entertainment systems, and more particularly to means for producing an alarm to be perceived by the headphone user.
Of the many types of stereo receivers, radio receivers, and record, disk and tape amplifier systems available, most are adapted to be used with headphones. Although the fidelity and a general quality of the audio information produced by such units is in many cases extremely good, many people find that appreciation of the fidelity and quality of the system can be best appreciated when using headphones in order to shield the desirable sound from ambient noises. Further, in many cases it is practically required that headphones be used especially when other activites prevent an individual from playing his receiver or the like aloud; or to allow others to engage in activity which would normally make it impossible for one to listen to his receiver or playback unit.
Accordingly, increasingly sophisticated headphones have been developed to fulfill the above-described needs. Recent headphone development efforts have been principally in two areas; firstly, to provide fidelity which will at least match that of the audio equipment to which the headphones are coupled; and secondly, the ability of the headphones to block out ambient noise as completely as possible.
To a great extent, both of these criteria have been met. High-quality headphones are available whose fidelity substantially matches, or exceeds, that of stereo receivers and playback units. In addition, a considerable amount of research and experimentation has produced headphones which block out ambient sound to an extraordinary degree.
Achievement of these goals has contributed a great deal to the enjoyment of stereophonically reproduced music and the like. Ironically, however, the achievement of these very goals has created a problem inasmuch as the better the noise-blocking qualities of the headphones, the more oblivious the user is to ambient sounds which he might otherwise wish to hear. For instance, a headphone user is often oblivious to a knock upon the door, or a doorbell ringing; and oftentimes cannot hear a telephone ringing or a child calling from a distant part of a house or an apartment. More importantly, he may also be oblivious to otherwise audible alerting signals, such as a fire alarm.
Accordingly, it will be seen that it would be highly desirable to provide means for alerting an individual to the occurrence of some unusual ambient sound, allowing him to temporarily remove the headphones and direct his attention to the source of the sound.
It is therefore an object of the present invention to provide means for alerting a headphone user to the occurrence of a substantial or unusual noise.
Another object is to provide a method of directing an alarm signal to a set of headphones in response to a perceived, unusual noise.
Yet another object is to provide means for superimposing an acoustic alarm signal upon audio information directed to a pair of headphones in response to the detection of a sound having a volume greater than some predetermined value.